International Mammalian Genome Society

The 15th International Mouse Genome Conference (2001)

Table of Contents * Complex Genetics * Developmental Genetics * Gene Annotation * Gene Discovery * Genome Sequencing * Functional Genomics * Mutagenesis * Presentations * Verne Chapman Memorial Lecture

Miss Rachel Smith
The Babraham Institute
Developmental Genetics Programme
Cambridge
CB2 4AT
United Kingdom

Co-Authors: Dean WL, Konfortova GD, Kelsey G
Institutions: Developmental Genetics Programme, The Babraham Institute

Methylation sensitive representational difference analysis was applied to parthenogenetic and normally fertilised mouse embryos in a genome-wide screen for regions of maternal-chromosome specific methylation.  Regions of parental-allele specific epigenetic modification such as this are associated with genes regulated by genomic imprinting and expressed from only one parental chromosome.

Amongst the many loci identified in this screen, two separate regions of imprinted methylation were found on distal chromosome 15. This is the first evidence of genomic imprinting on this chromosome.  These differentially methylated regions display characteristic sequence properties of imprinted genes - they are located at CpG islands, and GC-rich tandem repeats are present at one locus.  Transcripts have been identified at each of these loci and are currently being investigated.

One of the loci under investigation was mapped between D15Mit67 at 40.9cM and D15Mit105 at 47.9cM using radiation hybrids.  Transcribed from this locus is a non-coding, unspliced RNA of unknown function. The transcript is highly expressed in the brain, particularly in the hippocampus, and is also highly expressed in adrenal glands.  This novel imprinted gene is expressed exclusively or predominantly from the paternal allele in all tissues examined. The function of this transcript is under investigation by the use of gene targeting approaches.